For most of the world, it is an unsolved mystery. But for the families of the 239 people aboard that missing Malaysian jetliner, it is unmitigated agony.

In Beijing today, some of them threatened to go on a hunger strike - unless they got answers.

But 11 days after the Boeing 777 vanished on a flight from Kuala Lumpur to Beijing, answers are still hard to come by.

On Tuesday, sources told CBS News that checks of the computers and email of the captain and first officer turned up nothing to suggest a plot.

Still, there are indications that someone in the cockpit intentionally took Flight 370 off course. Sources now say there is evidence that the plane was turned off that original course after someone typed a course change into an onboard navigation system in the cockpit. This would suggest that someone had real training in the Boeing 777 systems, something far more sophisticated than simply turning a wheel.

Asked whether the plane's path in a western direction had been programmed in the aircraft's flight management system, the CEO of Malaysia Airlines said: "As far as we are concerned, the aircraft was programmed to fly to Beijing."

He said reports that the plane's flight path had been tampered with may have been speculation.Pressed on whether it was possible, he said, "Once you are in the aircraft, anything is possible."

That has only sharpened suspicion of the pilot Zaharie Ahmad Shah and the co-pilot, Fariq Abdul Hamid.

"Captain Zaharie is a person that enjoys his life, who loves doing things to make people happy," said Peter Chong, a friend of Zaharie who is quick to defend his friend.

A lot has been made of the fact that police found a flight simulator inside his house. Chong was asked who has a flight simulator in their house?"Anybody with aviation as their hobby - and you can afford it," Chong said.

Little is known about the co-pilot, but so far intensive background checks on the passengers and crew have failed to turn up any links to terrorism.

Criticism of the investigation is mounting, even within Malaysia.

"Right from the outset - immediately when the plane disappeared - they should have realized that this involved expertise which was beyond our capacity," said Sivarasa Rasiah, an opposition member of Malaysia's parliament.

He said Malaysia should have accepted offers of help from the United States and others sooner.

"I think if that had happened perhaps we might not have had the fiasco of wasting a week out in the South China Sea, looking in a place where we shouldn't have been looking in the first place," he said.

Now the real challenge is to refine that search area. China says that it has redeployed 21 satellites to help.